Resolving UML dichotomies

[Paolo F Cantoni]

I've posted my thoughts on some of the dichotomies in UML:
A navigable, named association end IS an attribute. (UML specification)
A client element connected by a nesting relationship to a supplier element IS a nested element (of the supplier) (UML specification)
An n-ary Association "lozenge" IS an Association Class (Paolo specification :-)).

And so on...?

Anyway, my question is:  As I'm emitting the model, should I just emit the "fact(s)" once or repeat them in both forms?

My current view is to emit them once only (single-point of definition, single representation), but I'd be interested in your views...

Cheerz,
Paolo